Abstract
Purpose: :
Retinal edema is caused by a breakdown of the blood-retinal barriers associated with an extravasation of serum albumin (vasogenic edema), and by an impairment of the fluid absorption from the retinal tissue. Osmotic swelling of Müller cells (cytotoxic edema; reflecting a disturbance in the water transport across Müller cell membranes) has been shown to occur in various animal models of retinal ischemia and inflammation. However, the relationship between vasogenic and cytotoxic edema in the retina is unknown. We investigated the effect of bovine serum albumin (BSA) on the osmotic swelling properties of Müller cells.
Methods: :
Acutely isolated slices of the rat retina were perfused with a hypoosmolar solution, in the absence and presence of BSA, and the size of the Müller cell somata was recorded.
Results: :
BSA acutely administered to slices of the rat retina caused a swelling of Müller cells under hypoosmotic conditions which was not observed in the absence of BSA. The effect of BSA was dose-dependent with a half-maximal effect at 10 nM, and was mediated by endocytosis, oxidative stress and the production of inflammatory lipid mediators. The BSA-evoked cellular swelling was prevented by agonists of glutamatergic and purinergic receptors.
Conclusions: :
It is suggested that serum albumin flowing through leaky vessel walls may induce a swelling of Müller cells under conditions when the retinal osmohomeostasis is disturbed.
Keywords: Muller cells • edema • receptors